This invention relates to dispensing cap constructions of the type intended to dispense liquid or cream products, and more particularly to constructions of the kind incorporating a screw cap having a discharge passage which is sealed by a stopper on a cap body.
In particular, the invention involves improvements in applicant's U.S. Pat. Nos. 3,598,285; 3,844,455; and 3,848,779.
All of the cap constructions disclosed and described in the above patents are of the same general type, as far as their operation and use are concerned. In particular, each device comprises a screw cap having a discharge passage which is carried on a cap body having an upstanding spout, which in turn carries a sealing pin or stopper that is receivable in the discharge opening of the screw cap.
While the above patented constructions operated in a generally satisfactory manner, a number of problems have been found to occur when dispensing certain types of products, particularly glues, adhesives, and the like.
Referring to the device shown in U.S. Pat. No. 3,848,779, there was a tendency, following the first few uses of the dispenser, for crusted product (glue) to harden over the area around the stopper or plug 20 and the surrounding area of the external surface of the screw cap 12. During subsequent use, as the cap 12 was unscrewed from the position shown in FIG. 1 to that shown in FIG. 7, the crusted product tended to adhere to the external surface of the cap, forming a dome over the discharge passage 26, this dome remaining sealed and intact, in many cases. As a result, further discharge of product through the opening 26 was prevented, and it was necessary to forcibly dislodge the dome, either with a flick of the user's nail, or by means of a suitable instrument or knife. Naturally, where the dispenser was being used frequently this represented an unnecessary waste of time, whereby the convenience of the dispenser was impaired somewhat.
The other alternative would be to wipe the stopper or plug 20 and surrounding surface of the cap 12 after each use, which was considered a nuisance from the standpoint of the consumer. Accordingly, the problem of product formation over the opening 26 arose from the fact that hardened glue tended to cling to the outer surface of the cap, and not to the plug 20, the latter having a relatively smooth cylindrical surface which tended to readily release hardened product without tending to cause it to break away.
The above disadvantages and drawbacks of prior dispensing cap constructions are obviated by the present invention which has for an object the provision of a novel and improved cap construction which is simple in its structure, reliable in use, and which greatly minimizes the tendency for crusted product to adhere to the surface of the cap and thus interfere with subsequent dispensing operations.
A related object of the invention is to provide a dispensing cap construction as above, wherein the parts can be readily molded of plastic, in relatively simple mold cavities.
A still further object is to provide a dispensing cap construction of the type having a turnable screw cap, wherein the cap can, from its full-on position, rotate through an angle on the order of 20.degree. or more prior to experiencing any outward axial movement, thereby intending to loosen any residual hardened product on its exterior surface adjacent its discharge opening.
Still another object is to provide a cap construction of the type having a stopper which is receivable in the discharge passage of a screw cap, wherein the stopper has a surface configuration of a generally non-smooth nature that tends to hold residual hardened product during initial rotation of the screw cap, thus causing breakage of the crust from the surface of the cap surrounding its opening.
Yet another object is to provide a screw cap construction which has a long life expectancy, and which lends itself to assembly by automatic capping equipment.
The above objects are accomplished by the provision of a captive dispensing cap construction comprising a tubular body part having a discharge passage and a stopper extending upwardly from the passage, and a screw cap part carried by the body part and having a discharge opening into which the stopper extends when the screw cap part is screwed to its full-on position. The screw cap and body parts have two pairs of mutually engageable portions, one pair comprising cooperable screw thread means for moving the screw cap part axially on the body part as the screw cap part is turned, and the other comprising a cam track on the body part and a follower portion on the screw cap part. A lug is disposed on the screw cap part, and there is a stop shoulder on the body part, engageable with the lug of the screw cap part to halt its turning as it is screwed to its full-on position. The screw thread means of the screw cap and body parts have sufficient backlash to enable the screw cap part to have an initial unscrewing turning movement from its fully screwed-on position without outward axial displacement, through an angle essentially in excess of 20.degree.. The stopper has an exposed surface configuration which tends to retain hardened or crusted product against dislodgement during the initial rotating movement until a forcible removal of the crusted product occurs by the outward axial displacement. The initial rotating movement tends to loosen previously crusted product from the screw cap part by virtue of the retention action of the surface configuration of the stopper. The cam track and follower portion also become effective to move the screw cap part axially outwardly after the cap part is turned through an angle essentially in excess of 20.degree.. The arrangement is such that the loosening of the previously-crusted product by the initial rotating movement, and the axially-outward movement of the screw cap part effect a dislodgement of hardened product both from the exterior surface of the screw cap part and from the stopper, thus greatly facilitating subsequent dispensing operations.
Other features and advantages will hereinafter appear.